1. Field of the Invention
The present invention generally relates to a lamp circuit and, more particularly, to a lamp circuit that supplies a voltage to a load based on a received voltage from a light-radiating module thereof.
2. Description of the Related Art
Conventional lamps generally comprise a light-radiating module which radiates light through light-radiating devices such as light-emitting diodes (LEDs), bulbs or light tubes. Since the light-radiating module generates a significant amount of heat during operations, cooling equipments such as fans or heat sinks are required for cooling the light-radiating module in order to prolong the service life of the lamp.
Apart from a load of the light-radiating module, the conventional lamps also comprise a direct current (DC) load. Generally, the DC load requires different supply voltage from the light-radiating module. Therefore, multiple supply voltages are irreversibly required in the lamps.
Referring to FIG. 1, a conventional lamp circuit is disclosed. The lamp circuit comprises a DC power supply 91, a driving unit 92 and a light-radiating module 93. The DC power supply 91 is electrically connected to the driving unit 92 which, in turn, is electrically connected to the light-radiating module 93. The DC power supply 91 generates a first voltage V91 that is provided to the driving unit 92. The driving unit 92 generates a constant DC current Ic that passes through the light-radiating module 93. With the constant DC current Ic, the light luminance of the light-radiating module 93 is kept in a constant level. The light-radiating module 93 comprises a feedback end 931 electrically connected to the driving unit 92. The light-radiating module 93 sends a feedback signal back to the driving unit 92 via the feedback end 931 such that the driving unit 92 may keep the constant DC current Ic passing through the light-radiating module 93 from varying based on the variation of the feedback signal.
A cooling fan 95 is required to be equipped in the lamp for cooling purpose as the light-radiating module 93 generates a significant amount of heat due to the constant DC current Ic passing therethrough. Since the cooling fan 95 requires different supply voltage from the light-radiating module 93, an additional supply voltage has to be provided therefor.
Referring to FIG. 1, the lamp circuit further comprises a voltage regulation unit 94 electrically connected to the driving unit 92 to receive a DC voltage therefrom. Alternatively, the voltage regulation unit 94 may also be electrically connected to the output ends of the DC power supply 91 to receive a first voltage V91. The voltage regulation unit 94 converts the first voltage V91 into a second voltage V92 that is provided to the cooling fan 95.
The conventional lamp circuit has some drawbacks. For instance, the conventional lamp circuit requires the voltage regulation unit 94 for providing the second voltage V92 to the cooling fan 95. In this regard, circuitry complexity and costs are increased.
Therefore, it is desired to improve the conventional lamp circuit.